Method of manufacturing synthetic filaments and the like



Aug. 22, 1950 K H. A. KULJIAN METHOD oF MANUFACTURING SYNTHETICFILAMENTS AND THE LIKE Filed Nav. 1s, 1947 NUM. QW

- 4 7 TURA/5y Patented Aug. 22, 1950 METHOD F MANUFACTURING SYNTHETICFILAMENTS AND THE LIKE Harry Asdour Kuljian, Merian, Pa.

Application November 13, 1947, Serial No. 785,626

8 Claims.

Synthetic filaments of the rayon type may be produced according to theviscose process, according to the cuprammonium process or according tothe cellulose acetate process. In all of these processes, it isnecessary to'protect the filament, in its nascent stage, from contactwith the oxygen of the air or with other gases which may produceunintended chemical reactions. In the case of the viscose process, inwhich the viscose solution is extruded into a bath containing sulphuricacid, the presence of oxygen in the coagulating bath also causeschemical reactions which produce free sulphur which tends to deposit onthe filament. When the filament is intended for use in wearing appareland the like, the sulphur must be removed from the filament before theother treatments necessary to bring the filament to the desired finishedstate can be initiated. Removal of the sulphur from the filament addsanother step to the manufacturing operation and thus increases the cost.Also, because removal of the sulphur involves the use of harsh chemicalsand because it delays the initiation of the finishing treatments, whichdesirably, Should begin as soon as possible after formation of thefilament, the deposit of sulphur on the filament, at least indirectly,adversely affects the quality of the filament.

It is therefore the main object of the invention to provide an improvedmethod of manufacture of synthetic filaments whereby the production offree sulphur in the coagulating bath is prevented, or materiallyreduced, and whereby the filament is protected from contact with oxygen,during its formative and nascent stages and while it is still in thecoagulatng bath.

A further object is to carry out the invention in a simple, eflicient,inexpensive and practical manner.

The single figure in the drawing is a highly diagrammatic view, partlyin section and partly in elevation, illustrating one manner ofaccomplishing the objects of the invention.

According to my invention, I provide means for deg-asifying thecoagulating bath, means for saturating the bath with an appropriateinert gas, and means for protecting the surface of the bath, fromcontact with air or other gases.

As is usual in the manufacture of synthetic laments, the appropriatesolution is forced, under pressure, through a spinnerette I0, into anappropriate coagulating bath I4 contained in a receptacle I5.

Conveniently, the top wall of the receptacle, or portion I6 thereof, isprovided with an access opening which is normally closed by a cover I'I,

hinged at I8. The free edge of the cover is spaced somewhat from theedge of the wall I6 to provide a passage for the filament 22. Thefilament emerging from the receptacle travels around godet Wheels 24 andmay then be taken up for storage or for further treatment depending onthe use for which the filament is intended.

In order to prevent formation of free sulphur and the 'deposit ofsulphur on the filament, I provide a conventional degasifying apparatusfor removing gases from the coagulating b-ath. The degasifying apparatusis connected by a pipe 30 to a reservoir 32 which contains a supply ofcoagulating bath liquid and is connected by a pipe 34 to a receiver 3E.During its passage from the degasifying apparatus to the receiver, theliquid is charged with CO2 gas, from a charger 40 which is connected tothe pipe 34 by means of a pipe 4I. The receiver 36 is connected by apipe 42 to the lower portion of the receptacle I5 and a pump P is cutintothis pipe for propelling the bath liquid from the receiver to thereceptacle I5. From the upper portion of the liquid bath, a pipe 43leads to a regenerator 44, and another pump P' is cut into this pipe forpropelling the bath liquid from the receptacle I5 to the regenerator 44.In the regenerator, the bath liquid is reconditioned, or reconcentrated,and is returned to the reservoir 32 through a pipe 6. If desired, a pumpcan also be cut into the pipe i6.

In addition to the CO2 charger 4B, I provide a pipe 48 which isconnected at 5t to a pipe 52 leading from a source of CO2. It will benoted that the discharge end of the pipe 48 which is below the level ofthe bath liquid, should be so located, and the pressure of the gasiowing therethrough should be so controlled that the CO2 bubblingupwardly through the bath liquid will not disturb or damage the fragile,nascent lilament. It will also be noted that the opening through whichthe filament passes is located above the level of the bath liquid and isrelatively small so that only excess gas can escape through thisopening. This insures the continuous presence of -a blanket of inert gason the surface of the bath and will prevent surface absorption of air orother gases by the bath liquid. The location and size of the filamentpassage can be criti cal when the inert gas used is lighter than air,but are not very important when CO2 gas, which is heavier than air isused. While I have found CO2 gas to be satisfactory, I may use otherinert gases such as nitrogen.

In addition to depositing on the filament, the free sulphur in thecoagulating bath also tends to clog the orifices of the spinnerettesused for extruding the solutions into the bath and, in order to overcomethis diiiiculty, it has been necessary to add chemicals to the bath tokeep the sulphur in solution. For example, cations, such as laurylpyridine chloride or lauryl pyridine sulphate have been used for thispurpose. These chemicals are expensive and have to be used insubstantial quantities thus adding to the cost of manufacture. By myinvention, the production of free sulphur is prevented or materiallyreduced, and accordingly, the need for means for preventing deposit ofsulphur on the orifices of the spinnerettes is eliminated or materiallyreduced.

It will be seen that by the simple expedient of' degasifying the bathand then saturating. it with an inert gas, and by blanketing the surfaceof the bath with inert gas to prevent reabsorption of oxygen by thebath, the productionv of free sulphur, and its consequent deposit on thefilament and on the spinnerette, are eliminated or greatly reduced, thuseiecting considerable saving in the cost of manufacture and improvingthe quality of the iinished lament.

While the invention has been described above in connection With themanufacture of a filament it is obvious that the type f object beingmanufactured has no bearing on the method disclosed and claimed whichcan be used whether the object being made is a filament, a sheet, a ropeor is of any other shape or configuration.

What I claim is:

1. In' the method of producing a synthetic filament by extruding aviscose solution into a liquid coagulating medium, the step ofpreventing formation of free sulphur in said medium and deposit of thefree sulphur on said filament by removing oxygen from said medium.

2. In the method of producing a synthetic filament by extruding aviscose solution into a liquid coagulating medium, the step ofpreventing formation of free sulphur in said medium and deposit of thefree sulphur on the filament, during 4 its formative stage, by removingoxygen from said medium and impregnating said medium with an inert gas.

3. The method recited in claim 2 in which the inert medium is carbondioxide gas.

4. The method recited in claim 2 in which the inert gas is nitrogen.

5. In the method of producing a synthetic lament by extruding a viscose,solution into a liquid coagulating bath, the steps of removing oxygenfrom said bath, and of blanketing the surface of said bath with aheavier than air inert gas to prevent absorption of oxygen by said bath.

6. In the method of producing a synthetic lament by extruding a viscosesolution into a liquid coagulating. bath, the steps of removing oxygenfrom said bath, replacing the oxygen with a heavier than air inert gas,and blanketing the surface of said bath with a layer of said inert gas.

'7. In the method of producing a synthetic lament by extruding aviscosev solution into a liquid coagulating bath, the steps ofcirculating said bath through a substantially closed circuit whichincludes a deaerating device for removing oxygen from said bath, forcinga heavier than air inert gas through said bath to replace the oxygen,and blanketing the surface of said bath with a layer of said gas.

8. The method defined in claim '7 together with the step of extrudingthe solution into a bath contained in a substantially closed receptacle.

HARRY ASDOUR KULJIAN.

REFERENCES CITED The following. references are of record in the file ofthisv patent.:

UNITED STATES PATENTS Number Name Date 2,241,304 Heywood et al. May 6,1941 2,335,922 reyfus Dec. '7, 1943 2,336,778 Costa et al. Dec. 14, 19432,413,102 Ebert et al. Dec. 24, 1946

7. IN THE METHOD OF PRODUCING A SYNTHETIC FILAMENT BY EXRUDING A VISCOSESOLUTION INTO A LIQUID COAGULTING BATH, THE STEPS OF CIRCULATING SAIDBATH THROUGH A SUBSTANTIALLY CLOSED CIRCUIT WHICH INCLUDES A DEAERATINGDEVICE FOR REMOVING OXYGEN FROM SAID BATH, FORCING A HEAVIER THAN AIRINERT GAS THROUGH SAID BATH TO REPLACE THE OXYGEN, AND BLANKTING THESURFACTOF SAID BATH WITH A LAYER OF SAID GAS.